I have 121 GB Storeage in 77 GB is occupied by Others folder, which can not open and mac book is no space.

Files under the "Other" category are files that do not belong to any other category, and your Mac cannot classify as either Documents, Pictures, Videos, Apps, etc. or System Files. These may be Temporary Files, and Installation packages (.dmg and .pkg files), among others

A very quick way to empty some space on your Mac is to delete Cached Files.

To do that, open your Finder and press Shift + Command + G (or go to "Edit" > "Go").

Type ~/Library/ and press return

Find the folder "Caches" and single-click it.

Press Option + Command + Backspace and confirm the deletion.

Option + Command + Backspace deletes the files without sending them to the Bin first. However, you can do it the good ol' way, by right-clicking and selecting "Send to Bin", then opening the Bin and emptying it.

Cached Files are files that have been temporarily stored by apps or the Operating System to perform certain actions. Usually, after completing their operations, the programs delete their Cached Files, however sometimes they may leave some data behind. It is generally safe to delete the Caches folder. It also accumulates for quite a large percentage of the "Other" Category Files. However, as the "Caches" folder is located in an area where other system files (essential for your Mac to function properly) are stored, you should be extra cautious, not to delete something else in the process. You may be asked to enter your password or confirm with Touch ID (if your Mac supports it).

After deleting the cache restart your Mac and check your storage to see how much space this emptied.

You might also want to empty your bin, try uninstalling apps taking up a large amount of space etc.

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-flef

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The final word from Apple on Managing the " Other/ System Data “ Category

Other / System Data: Contains files that don’t fall into the categories listed here. This category primarily includes files and data used by the system, such as log files, caches, VM files, and other runtime system resources. Also included are temporary files, fonts, app support files, and plug-ins. You can't manage the contents of this category. The contents are managed by macOS, and the category varies in size depending on the current state of your Mac.

See Kappy’s advice What is "Other" and What Can I Do About I… - Apple Community

I also had this on my 128gb macbook air. This is just very little storage so I started using iCloud and when I want to store locally I have a Mac mini wich acts as server for my files for now.

What me helped with the full other categorie is reinstalling the system

Other is not a folder or a location. It's a catch all category for files that don't match the most common types.

It's an indicator that you bought a MacBook Air with the minimum sized 128 GB SSD, too small for any practical use other than email and surfing the Internet.

By the way, you posted to the wrong forum area, this forum area is for 12" Retina MacBooks, not MacBook Airs.

It's spelled, "storage," not, "storeage."